Integral bodyshell structure for a motor vehicle and method of producing the bodyshell structure

ABSTRACT

Integral bodyshell structure for a motor vehicle and method for its production. Known vehicle bodyshell structures are composed of a multiplicity of individual sheet-metal stampings, and as a result complex joining processes for the sheet-metal shell construction arise. In the invention, first the inner side-wall part is joined on each side to the under-frame assembly and then the outer side-wall parts are added. This method has applications for the production of passenger cars.

The invention relates to an integral bodyshell structure for a motorvehicle, in particular a passenger car, with an underframe assembly, aside-wall assembly which has two side walls, and a roof assembly, and toa method for the production of the bodyshell structure.

Vehicle bodyshell structures of sheet-metal shell construction areknown, these being composed of a multiplicity of individual sheet-metalstampings (Mercedes-Benz W 201). In this case, the complete side wallsare composed of individual sheet-metal parts of the A-, B- and C-pillars, as well as of the lateral roof frames and sills. Thesesheet-metal stampings, of which there are a large number, have to beconnected to one another in a manner which is relatively complex duringassembly of the side wall. For reinforcements in the joint regions andfor joint connections to the end supports, for example in the region ofthe front and rear roof transverse supports, relatively complex guidesare required.

It is also known (German Patent 692 243) to construct the side walls ofa motor vehicle from a respectively integral, outer and inner side-wallpart, which parts are connected to one another. Motor vehicles of thistype do not, however, have an integral bodyshell structure.

The object of the invention is to provide an integral bodyshellstructure of the type mentioned at the beginning as well as a method forits production, which structure and method ensure that production isof-little complexity and that nevertheless the various parts of thebodyshell structure are assembled precisely.

This object is achieved for the integral bodyshell structure in thateach side wall is composed of an inner side-wall part and an outerside-wall part which are integrally joined together, and in that, on itstwo sides facing the inner side-wall parts, the underframe assembly isprovided with fastening flanges which are assigned to correspondingfastening regions of the inner side-wall parts in such a manner that theside-wall parts can be aligned in the longitudinal direction of thevehicle relative to the underframe assembly for tolerance-freepositioning. This makes it possible, during production of the bodyshellstructure, to fit the inner side-wall parts from the sides to theunderframe assembly, which has already been finished, and before theyare welded to the underframe assembly to align them relative to theunderframe assembly in such a manner in the longitudinal direction ofthe vehicle that each inner side-wall part is positioned precisely onthe respective underframe assembly. The alignment of the fasteningflanges is selected such that the fitted, inner side-wall part can bedisplaced on each side of the underframe assembly sufficiently far inthe longitudinal direction of the vehicle for precise, tolerance-freepositioning relative to the underframe assembly to be achieved.Subsequently placing the outer side-wall parts onto the inner side-wallparts, which have already been positioned precisely and are connected inthis position rigidly to the underframe, results in a very precisevehicle body, i.e. a bodyshell structure produced essentially free oftolerances is provided.

In a development of the invention, the fastening flanges are alignedrelative to the fastening regions of the side walls in such a mannerthat it is possible additionally for the side walls to be aligned in avertical direction relative to the underframe assembly. This makes itpossible also to compensate for tolerances in the vertical directionbetween the underframe assembly and the inner side-wall parts, thusresulting in a further improvement in assembling the bodyshell structureprecisely.

For the method for the production of the bodyshell structure, the objectaccording to the invention is achieved in that first the inner side-wallpart is joined on each side to the underframe assembly as an integralcomponent, and, as it is joined, fastening in at least one rooftransverse support of the roof assembly, and then the outer side-wallparts are added in each case as integral components. By virtue of themethod according to the invention the complete, supporting structure ofthe vehicle body is already provided by the first method ormanufacturing step. The subsequent fitting of the outer side-wall partsessentially constitutes merely panelling the already provided supportingstructure. The assembly sequence according to the invention means thatfewer component parts have to be put in place. An essential advantage ofthe invention is that complex joining processes for reinforcements andjoint-joining connections are dispensed with since all of the jointconnections to the joining supports as well as the requiredreinforcements with the underbody can be realised in a simple manner byvirtue of the easy accessibility. These measures result in a reducedmanufacturing time, simpler and hence lighter and cheaper reinforcementparts, a reduction in the bodyshell tolerances and thus, inevitably, areduction in the complexity of production.

In a development of the invention, the outer and inner side-wall partsare each produced from a plate-welded semi-finished product. The outerand inner side-wall parts are each produced as integral components,thereby enabling complex connecting flanges to be dispensed with. Thisleads to a reduction in the complexity of production and to a reductionin the weight of the bodyshell structure.

In a further development of the invention, the outer and inner side-wallparts are each produced from a sum total of component parts. In thiscase too, the outer and inner side-wall parts composed of the sum totalof component parts are joined together in advance to form integralcomponents which are then fitted to the under-frame in the assemblysequence according to the invention.

In a further development of the invention, reinforcements which arerequired depending on the type of vehicle are inserted on each side,between the outer and the inner side-wall part. These reinforcements areinserted either in the outer or in the inner side-wall part and theinsertion points are easily accessible.

In a further development of the invention, the roof assembly has a roofand at least two roof transverse supports which are inserted between theopposite, inner side-wall parts before the roof is put on. Theseroof-support parts, which are arranged on the inside, are expedientlyinserted between the inner side-wall parts at the same time as the innerside-wall parts are being joined to the underframe assembly. As aresult, the entire inner supporting body of the passenger cell isproduced in one manufacturing step, thus enabling, in a next step, therespectively outer parts of the bodyshell structure to be joined on in asimple manner.

Further advantages and features of the invention emerge from thesubclaims and from the description which follows of preferred exemplaryembodiments of the invention, which are illustrated with reference tothe drawings, in which

FIG. 1 shows schematically, in an exploded illustration, the assemblysequence step for producing a bodyshell structure, according to theinvention, for a passenger car, in accordance with an embodiment of themethod according to the invention in which the inner side-wall parts arejoined onto the underframe assembly,

FIG. 2 shows a section through the finished bodyshell structure of thepassenger car according to FIG. 1, at the level of the intersecting lineII--II illustrated in FIG. 1,

FIG. 3 shows a section along the intersecting line III--III through thepartially completed bodyshell structure according to FIG. 1, in whichthe inner side-wall part is joined onto the underframe assembly,

FIG. 3a shows a sectional illustration corresponding to FIG. 3 through afurther bodyshell structure similar to FIG. 1, in which a fasteningflange of the underframe assembly, which is intended for the fitting ofa corresponding fastening region of the inner side-wall part, is bentdownwards,

FIG. 4 shows a further exploded illustration of the bodyshell structureof the passenger car according to FIG. 1, in a subsequent assemblysequence step, in which the outer side-wall parts are joined to theinner side-wall parts which have already been connected to theunderframe assembly, and

FIG. 5 shows a section through the finished bodyshell structure of thepassenger car according to FIGS. 1 and 4, at the level of theintersecting line V--V in FIG. 4.

A bodyshell structure for a passenger car has an underframe assembly(1), according to FIGS. 1 and 4. The underframe assembly (1) of theintegral bodyshell structure is provided with a front part andsubsequent thereto with a scuttle (3). In addition, the bodyshellstructure has a left-hand and a right-hand side wall consisting in eachcase of an inner side-wall part (2) and an outer side-wall part (7).Reinforcements (5, 12), which are specific to the type of vehicle, areinserted on each side between the inner and outer side-wall parts (2, 7)(FIGS. 2 and 5). Each inner and each outer side-wall part (2, 7) can beproduced from a plate-welded semi-finished product, it being possiblefor the semi-finished product that is to be used to be a single-part ormulti-part plate, depending on the arrangement of strength. It is alsopossible for the individual sheet-metal parts, which are essentiallyknown, of the side-wall parts to be joined together by in each case onelarge sheet-metal part. FIG. 1 only illustrates the inner side-wall partwhich is on the left in the direction of travel. However, it goeswithout saying that the right-hand, inner side-wall part (2) isconstructed in a correspondingly symmetrical manner and is also joinedin the same manner to the underframe assembly (1). The same applies tothe left-hand, outer side-wall part (7) illustrated in FIG. 4. The roofassembly of the bodyshell structure consists of a front roof transversesupport (8) and a rear roof transverse support (9) as well as of a roof(10).

For the production of the bodyshell structure, the inner side-wall parts(2) are joined on both sides to the underframe assembly (1), after thelatter has been finished. In addition, during this assembly sequencestep, the front and the rear roof transverse supports (8, 9) areinserted, level with the roof frames of the inner side-wall parts (2),between the opposite, inner- side-wall parts (2). As a result, theentire, supporting body of the bodyshell structure is already obtainedwith the first assembly sequence step. Panelling, in the form of theouter side-wall parts (7) and the roof (10) of this supporting body, isthen carried out in the subsequent, second assembly sequence step.

As can be seen from FIG. 3, each inner side-wall part (2) is joined insuch a manner to the underframe assembly (1) that a sill (17) in theform of a U-shaped inwards indentation of a profile of the innerside-wall part (2) is situated on the underbody of the underframeassembly (1). In order to fasten the inner side-wall part (2) to theunderframe assembly (1), the underframe assembly (1) is provided on itstwo opposite sides with fastening flanges (13, 14) (FIGS. 1, 2 and 3),which flanges are aligned in such a manner relative to the correspondingfastening regions (15, 16a) of the inner side-wall part (2) that theyallow a certain displacement in the longitudinal direction of thevehicle, i.e. referring to the coordinate system according to FIG. 1, inthe X-direction. In this case, the fastening flange (13) is positionedin a vertical longitudinal plane of the vehicle, behind the scuttle inthe longitudinal direction of the vehicle. The fastening flange (14)protrudes laterally outwards in a horizontal plane from the underbody.The upper side of the sill (17) forms the corresponding fastening region(16) of the inner side-wall part (2) which, when the inner side-wallpart (2) has been fitted, likewise runs horizontally and bears in asheet-like manner from below against the fastening flange (14). Thisfastening flange (13) is fitted onto an A-pillar section (18) of theinner side-wall part (2), which section is correspondingly aligned in avertical longitudinal plane of the vehicle. The A-pillar section (18)provides the inner profile shell of the subsequent A-pillar. The outerprofile shell is completed by a corresponding A-pillar section (19) ofthe outer side-wall part (7). In order to obtain a U-shaped profile forthe inner A-pillar section (18) in the joining region of frontlongitudinal members (which are not shown), there is then provided,towards the front of this section (18), a shaped portion (4) whichcurves outwards towards the outer side-wall part (7). The outerside-wall part (7) has a corresponding impressed portion (6) by means ofwhich the U-profile, corresponding to the A-pillar section (18), isformed for the outer A-pillar section (19). As can be seen in FIG. 2,this results in the box-shaped cross-section of the A-pillar. Toreinforce the A-pillars and the front longitudinal members,reinforcement plates (5, 12) are fastened between the two side-wallparts (2, 7) in the region of the A-pillar sections (18, 19), thereinforcement (12) continuing into the front longitudinal member, as canbe seen from FIG. 5. The sheet-like arrangement of the inner side-wallpart (2) with its fastening regions (15, 16) on the fastening flanges(13, 14) of the underframe assembly (1) enables the side-wall part (2)to be aligned, before it is welded to the underframe assembly (1), inthe longitudinal direction of the vehicle in such a manner that theside-wall part (2) is aligned precisely relative to the correspondingparts of the underframe assembly (1) and is positioned in atolerance-free manner.

The sectional illustration according to FIG. 3a essentially correspondsto that of FIG. 3. However, in this underframe assembly (1) thefastening flange (14a) is folded downwards, the vertically aligned baseof the sill (17) thus producing the relevant fastening region (16a) ofthe inner side-wall part (2). This enables the inner side-wall part (2),in addition to the displaceability in the longitudinal direction of thevehicle (X-direction), also to be positioned precisely in the verticaldirection (Z-direction), additional opportunities to compensate fortolerances before the underframe assembly (1) and the inner side-wallparts (2) are welded together thus being provided. For fastening theinner side-wall part (2) to the underframe assembly (1), the innerside-wall part (2) can therefore first be fitted to the underframeassembly (1) transversely with respect to the longitudinal direction ofthe vehicle, i.e. in the Y-direction, and can then be precisely alignedeither exclusively in the X-direction (FIG. 3) or both in theX-direction and in the Z-direction before it is welded to the underframeassembly (1).

In a next working step of the assembly sequence concept, the outerside-wall parts (7) are then joined to the inner side-wall parts (2)after the corresponding reinforcements (5, 12) have been inserted andpositioned between the two side-wall parts corresponding to FIGS. 2 and5. The roof assembly is completed by putting the roof (10) onto the rooftransverse supports (8 and 9) and onto the lateral roof frames of theside walls. In a further assembly sequence step, additional panellingparts are then fitted to the bodyshell structure, to be precise, inparticular in the region of the front part mud-guard panelling parts(11) are fitted to the side walls (2, 7).

Instead of inserting reinforcements, it is also possible to leave openspecially stressed zones in the main pressed parts of the side walls andto insert the corresponding reinforcements at a later stage.

We claim:
 1. A method for producing an integral bodyshell structure fora motor vehicle having an underframe assembly, a side wall assemblyhaving two side-walls each of which is composed of an inner side-wallpart and an outer side-wall part, and a roof assembly, the methodcomprising the steps of:first integrally joining the inner side-wallpart of each side wall to a respective side of the underframe assembly;while performing said integrally joining step, fastening at least oneroof transverse support of the roof assembly to the bodyshell structure;and adding the outer side-wall part for each side wall to a respectiveside of the bodyshell structure as an integral component.
 2. The methodaccording to claim 1, wherein the outer and inner side-wall parts areeach produced from a plate-welded product.
 3. The method according toclaim 1, wherein the outer and inner side-wall parts are each producedfrom a sum total of component parts.
 4. The method according to claim 1,further comprising the step of inserting reinforcements on each side ofthe bodyshell structure between the outer and inner side-wall parts. 5.The method according to claim 3, further comprising the step ofinserting reinforcements on each side of the bodyshell structure betweenthe outer and inner side-wall parts.
 6. The method according to claim 4,wherein said reinforcements are connected to the inner side-wall partsbefore the outer side-wall parts are joined on the bodyshell structure.7. The method according to claim 5, wherein said reinforcements areconnected to the inner side-wall parts before the outer side-wall partsare joined on the bodyshell structure.
 8. The method according to claim1, wherein said roof assembly includes a roof and at least two rooftransverse supports, said at least two roof transverse supports beinginserted between opposite, inner side-wall parts on the bodyshellstructure before said roof is put on.
 9. An integral bodyshell structurefor a motor vehicle, comprising:an underframe assembly; a side-wallassembly having two side walls; a roof assembly; wherein each of the twoside walls is formed of an inner side-wall part and an outer side-wallpart, said inner side-wall part having fastening region means forlongitudinally aligning said inner side-wall part relative to saidunderframe assembly by allowing both forward and rearward displacementof said parts relative to one another; wherein the underframe assemblyhas fastening flange means, on its two sides facing said inner side-wallparts, for longitudinally aligning said inner side-wall parts relativeto said underframe assembly by allowing both forward and rearwarddisplacement of said parts relative to one another; wherein saidfastening flange means are assigned to corresponding ones of saidfastening region means.
 10. The integral bodyshell structure accordingto claim 9, wherein said fastening flange means are aligned relative tothe fastening region means of the inner side-wall parts such that saidinner side-wall parts are additionally alignable in a vertical directionrelative to the underframe assembly.
 11. The integral bodyshellstructure according to claim 10, wherein said bodyshell structure is apassenger car bodyshell structure.